MOSCOW (AP) — Russian President Vladimir Putin called for a compromise Thursday to ease tensions over a plan to build a Russian Orthodox cathedral in a popular park in the nation’s fourth-largest city that has sparked protests and drawn nationwide attention.

Unsanctioned protests in the Ural Mountains city of Yekaterinburg have been held for four consecutive days near a central park where two local tycoons are planning to build a new cathedral. Several dozen protesters have been detained and 21 of them have been handed jail terms ranging from two days to 10 days for disobeying police.

The protests reflect local outrage after authorities pushed ahead with the project despite complaints that the massive church would take away a rare green, recreational space in the city of 1.5 million people. The standoff also reflected the growing power of the Russian Orthodox Church, whose increasingly assertive stance about secular affairs has worried many in Russia.

Asked about the controversy, Putin said authorities must reach out to opponents of the project and work out a compromise.

“The local residents’ opinion must be taken into account,” Putin said. “A cathedral must help unite people, not cause a rift.”

The president suggested an opinion survey to determine public attitudes about the project.

Yekaterinburg Mayor Alexander Vysokinskiy went to a square near the park where protesters were gathering and promised to hold a survey and halt the construction project pending its results.

“We need to bring the process into a civilized framework ... we don’t need clashes and arrests,” the mayor said, surrounded by protesters chanting “Shame!” and “Resign!”

Protests in Yekaterinburg marked a rare example of defiance of the authorities in Russia, where harsh laws handing out criminal punishments for taking part in unsanctioned rallies have discouraged many from joining them.

In an apparent reaction to the showdown, the mayor of Krasnoyarsk, a major city in Siberia hundreds of miles east of Yekaterinburg, ditched plans to build a similarly large Russian Orthodox cathedral in the city center, citing the lack of green spaces. In Nizhny Novgorod, a city on the Volga River, several people took to the streets with banners in support of Yekaterinburg’s park defenders.

Critics saw the Yekaterinburg cathedral project as a glaring example of government authorities and business groups teaming up to the detriment of the public.

Alexei Navalny, Russia’s leading opposition leader, on Thursday released an investigation into the wealth — including a lavish London mansion — of Igor Altushkin, a billionaire tycoon who is sponsoring the Yekaterinburg cathedral project. He pointed out that Yekaterinburg has plenty of old Orthodox churches, many of them neglected, and argued that the plan for a new cathedral was driven by Altushkin’s ego.

Citing public documents, the Russian website The Bell reported that the Yekaterinburg cathedral is part of a larger development project that includes a business center and a nearby hotel.

Putin spokesman Dmitry Peskov has refuted the reports, saying that he had spoken to the developer and that there were no such plans.

The Association of Popular Resistance, a fringe radical group, said its activists hurled flares at the Moscow residence of the Russian Orthodox church’s head, Patriarch Kirill, and demanded in a banner his apology for the Yekaterinburg cathedral project.